Observations on pushing and aggression in pairs of hens in battery cages

An experiment was designed to test in two strains of chickens whether aggression and pushing behaviour in pairs of hens depended on the amount of available space in battery cages. There was essentially no aggression and cage areas had no effect on the frequency of aggressive pecks. Pushing behaviour (which was reciprocal) was often observed in the battery cages, but its frequency was not affected by density. Most results were similar for the 2 strains. Post-experimental observations confirmed these results. Feather-pecking was largely absent in pairs of the light strain whereas it was significantly affected by floor area in pairs of the medium strain, i.e. most frequent at intermediate cage areas. Inter-cage aggressive pecks were significantly more frequent than intra-cage ones.